1. Field of the Invention
The present invention relates to a refrigeration system and method, and more particularly to a residential refrigeration system and method having improved energy efficiency.
2. Discussion of the Related Art
A typical refrigerator has a freezing compartment for maintaining food temperatures below 32.degree. F., and a cooling compartment for maintaining food below an ambient temperature and above 32.degree. F. Normally, a mechanical thermostat in a space between the freezing compartment and the cooling compartment determines when a compressor in the refrigerator is activated. A manually operated mechanical damper regulates the amount of cold air transmitted from the freezing compartment to the cooling compartment to control the temperature differential between the compartments.
Sudden increases in load due to opening doors or placing warm objects into the compartments require refrigeration capacity far in excess of normal operation. Maximum capacity is determined by the size of the evaporator, condenser, and compressor of the refrigerating system. Each time the thermostat switches on, the system is operated at its maximum capacity causing temperature swings inside the compartments as large as 10.degree. F. Thus, in response to sudden increases in load, prior art refrigerators exhibit a large positive temperature swing, a long recovery cycle and an overshoot in compartment temperatures. When the temperature overshoots below the desired set point, energy is lost through the cabinet and the refrigeration system uses more energy to achieve the differential between temperature of the compartments and ambient temperature.
Defrost of the evaporator coil by an inefficient electric resistance mechanism is another source of energy inefficiency in the typical prior art refrigerator.